Acetylation of cellulosic materials.



JOSEPH KoETsoHE'r AND MAX THEUMANN, or LYON, FRANCE, ASSIGNORS TOSOGIETE oHIMIoUE :ons USINES DU RHONE, ANCIENNEMEN'I. GILLIARD, r.MONNET ET CARTIER/,0]? PARIS, FRANCE.

ACETYLATION OF CELLULOSIC MATERIALS.

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reaction with cellulose and its hydrates.

All these processes have the disadvantage that it is diflicult torecover the surplus anhydrid.

We have discovered that acetyl celluloses can be very easily prepared bycausing the acetylizing agent to act in the form of vapor upon celluloseand its hydrates.

This process presents two main advantages:-(1) The acetyl cellulosesobtained retain the structure of the starting product. (2) The surplusanhydrid and the acetic acid formed can be readily recovered.

For carrying out the process, the vapors of the acetic anhydrid arebrought into contact with the heated cellulose at a suitabletemperature, which may with advantage correspond approximately to thesaturation or condensation point of said vapors.

The action of the anhydrid at boiling temperature (137 C. under ordinarypressure) is very vigorous, and it may be moderated by reducing thepressure or by diluting the anhydrid vapors with suitable gases orvapors. Inany case the surplus anhydrid and the acid formed may bereadily recovered by condensing the vapors escaping from the acetylizingapparatus.

The acetyl cellulose formed, which in this process does not go intosolution, retains the structure of the original material. As startingmaterial we may employ cotton, paper, wood pulp, and other celluloses,mercerized or not, and also hydrocelluloses or cellulose hydrates, suchmaterials being hereinafter included in the term cellulosic body. Thematerials can be used dr or more or less moistened with water or ilutedsolutions of or anic or mineral acids.

xample 1: In a cylindrical vessel connected at its upper partto acondenser and a Specification of Letters Patent. Patented June 25, 1912.Application filed DecemberS, 1911. Serial No. 664,673.

C. and the pressure-is reduced in order to produce abulition at the saidtemperature. The anhydrid vapors in their passage through the cottonconvert the same rapidly into acetyl cellulose, and the issuing vaporsare condensed. The reaction is terminated as soon for example as a testsample is soluble in chloroform; the anhydrid vapors are then exhaustedfrom the vessel and the acetyl cellulose formed is worked up in theknown way, that is to say, is thoroughly washed with water and dried.

Example 2: 100 grams of cotton are impregnated with 20 grams of a 3 percent. sulfuric acid. The cotton thus prepared is completely acetylizedby a three hours treatment with anhydrid vapors at 40 C. The acetylcellulose formed has the appearance and strength of the cot-tonemployed, and is soluble in chloroform, acetone, tetrachlorethane andglacial acetic acid. The solutions are viscous; films made therefrom aredurable and elastic.

Example 3: 100 grams of cotton are impregnated with 20 grams of a '1 percent. sulfuric acid and treated as in the last example. The acetylationisterminated after 50 hours. The product has the appearance though theacetyl cellulose is notgelatinized.

Glacial acetic acid.- may be em loyed instead of water for dilutihg thesull uric acid; this modification has the advantage that no aceticanhydrid is destroyed. On the other hand the sulfuric acid can besubstituted by other mineral acids or by organic acids; for examplesulfo-aoetic acid or aryl sulfo acids, diluted with water of glacialacetic acid, may be'employed. Any agents may be employed which assistthe hydrolysis or acetylation of the cellulose.

What we claim as our invention and desire to secure by Letters Patent is'1. A process for acetylizing a cellulosic body, comprising subjectingthe same to the action of acetic anhydrid vapors.

2. A process for acetylizing a cellulosic anhydrid Vapors.

5. A process for acetylizing a cellulosi'c body, comprising treating thesame with an acid, and subjecting the material so treated to the actionof acetic anhydrid vapors.

6. A process for acetylizing a cellulosic body, comprising treating thesame with sulfuric acid, and subjecting the material so treated to theaction of acetic anhydrid vapors.

7. A process for acetylizing a cellulosic body, comprising treating thesame with a dilute acid and subjecting the material so treated to theaction of acetic anhydrid vapors at reduced pressure.

8. A process for acetylizing a cellulosic body, comprising treating thesame with an acetylation promoting agent and subjecting the material sotreated, and in a heated state, to the action of acetic anhydrid vapors.

9. A process for acetylizing a cellulosic body, comprising treating thesame with an acid and subjecting the material so treated, and in aheated state, to the action of acetic anhydrid vapors.

10. A process for acetylizing a cellulosic body, comprising treating thesame with an acid, subjecting the material so treated, and in a heatedstate, to the action of acetic anhydride vapors, and recovering thesurplus acetic anhydrid.

11. A process for acetylizing a cellulosic body, comprising treating thesame with an acetylation promoting agent, subjecting the material sotreated, and in a heated state, to the action of acetic anhydrid vaporsunder reduced pressure, and removing and condensing surplus aceticanhydrid.

12. A process for acetylizing a cellulosic body, comprising treating thesame with a diluted sulfuric acid, subjecting the material so treated,and in a heated state, to the action of acetic anhydrid vapors underreduced pressure, and extracting and condensing surplus acetic anhydrid.

In testimony whereof we have signed our names to this specification inthe presence of two subscribing witnesses.

- JOSEPH KOETSCHET.

MAX THEUMANN.

Witnesses:

.1110. N. BROWN, jJULraN TIGUET.

